The invention is directed to a holder for cutting tool inserts, particularly for carving or cutter bits, with a gripper slot, which in each case holds inserts and the opposite jaws of which have an oval slotted area, into which a prop-open key with an elliptical cross sectional profile can be inserted and turned.
It can be inferred from the German Offenlegungsschrift No. 34 20 653 that a gripper slot 2 of the tool support 1 is expanded at the end into a circular opening 3 (see FIG. 1 there), into which a locking plate 12 with two corresponding circular locking strips 13, 15 can be inserted according to FIGS. 4 and 5 there. This locking plate has a hexagonal borehole 17, by way of which it can be moved either into the unlocked position (see FIG. 4) or the locked position (FIG. 5) by means of a corresponding hexagonal key. In accordance with one development of the invention (see below), such an additional effort is avoided, because the specific cross sectional profile is combined structurally, according to this development, with the key itself.
Pursuant to the German Offenlegungschrift No. 31 33 029, a gripper slot 106 of a tool holder is constricted by means of a cam part 130. The cam part 130 has a circular cross sectional profile, which has a flattened segment 132. Here also, a hexagonal opening 131 is provided once again for a separate key, in order to move the opposite gripping surfaces 108, 110 of the gripper slot towards one another.
The German Offenlegungsschrift No. 30 44 790 shows in FIG. 4 an ejection lever 15 with an ejection shoulder 16, which is intended to be used in the recess 6 of the tool holder 1. The recess 6 once again has a circular profile, while the ejection shoulder 16 essentially is longitudinal. The ejection shoulder 16 has elongated, parallel sides, which are connected at their opposite ends in each case by rounded off bends. The purpose of the elongation is to press the ejection shoulder 16 with its rounded off narrow side or bend against the back of the cutter bit 8 when the handle 14 is turned, so that this cutter bit 8 is ejected out of its binding seat.
The teachings that can be inferred from the European Patent No. 259 847 agree essentially with those of the above German Offenlegungsschrift No. 31 32 029. As shown in the drawing, a wedge element 17 is inserted in the borehole 16. By means of the screw 18, the wedge element 17 can be adjusted so that the (upper) clamping jaw 7 is swivelled in the direction of the arrow 19 against the cutter bit S. As a result, the cutter bit S is gripped fast in its gripper slot 6. In column 3, line 42 of this reference, those skilled in the art are induced to construct the wedge element 17 as a cam or cone. The borehole 16, which accommodates the wedge element, is provided with a circular cross sectional profile.
Holding plates of the initially named type, which are slotted in fork-like fashion, are known from the European Patent No. 0 095 062. The propping open of one clamping jaw relative to the other opposite clamping jaw is brought about by the insertion and twisting of an elliptical key in the ovally shaped region of the gripper slot (oval slot region). However, a precise geometric shape of the oval slot region of this known holder is not specified. Consequently, an excessive propping open of the gripper slot, during which the yield point of the material is exceeded, cannot be avoided with certainty with this type of holder system. Rather, it may come to permanent deformations, particularly of opposite clamping jaws, with the consequence that a stable gripping of the tool inserts no longer is guaranteed. Moreover, the ease of inserting and/or turning the key web is made difficult in the known embodiment because of the course of the profile of the oval slot region, which is fitted only roughly to the elliptical shape of the propping open key.